Railway signaling



March 22 1927.

s. LUCAS RAILWAY SIGNALING Original Filed Sept. 29 2 Patented Mar. 22, 1927.

ED SFTATEs PATENT o-FFicE.

SAMUEL LUCAS, or PITTSBURGH, rennnsrnvnnra, ASSIGNOR TC" THE" Union swITcH sasIeNAL COMPANY, on SWISSVALE, PENNSYLVANIA, A oonronATIon OF PENNSYLVANIA.

RAILWAY SIGNALING.

Applicationfiled'September'29; 1922, Serial No. 591,252. Itenewed Deeem-berfi; 1926.

Mvinvention'relates to railway signaling;

and? particularly to signaling of the type comprising-light signalscontrolle'd by threeposition relays 5 One'feature of my im ention-is the' provisiorr o fanovel means for preventingjmo'mentary" lighting o'if the stop lamp in a systemi matic view showing one form of signaling 1 system embodyingmy; invention;

Referring to the drawing, the reference characters K and L designate'the 'traclr rails of a railway over which tra-flic normally moves in the" direction indicated by the arrow. These rails are divided byinsulated jointsi2Q into a plurality of track sections A;B; Bf e, etc. Each track section is provided with a source of track circuit current which, as here shown, is a secondary winding 11 of a transformer designated by the reference character U with anexponent corresponding to the location, this secondary being'connected across the rails at the exit end ofthe section. Interposed between this secondary winding 11. and theupper rail'of each section is an impedance 10. One function ofthis impedance is to limit the current output of the transformer U to a safe value when short circuited by a train in the sec tion. Each section is also provided with a track relay which is designatedbythe refer-'- ence character X with an exponent corresponding' to the location; each of these re lays comprises a track winding 2 connected 40 across the rails adjacent/the entrance end of the section,and alocal winding 1 constantly supplied with alternating, current from atransin'ission line D which is fed by a generator J. It will thus be seen that each track section is provided with a track circuit comprising a transformer secondary 11 and a track relay winding 2.

Each relay X comprises two contact fingers 17' and 18 which are controlled byth'e currents in the relay windings 1 and" 2. Each relay is responsive to reversals 0t the -rela' tive polarity of thecurrent supplied to the" track winding 2. When current of normal relative polarity is supplied to. this-winding the relayis energized in-what I willterm: normal direction, and when. thus energized'the contact fingers 17 and-18 are-sWungj to the left; so that contacts 17 -3 and1'8-6 are closed; the'e contacts I will therefore" term the normal contacts of the relay: When the track winding 2 is supplled with current of reverse relative polarity, theme: lay is energized in what I will termreversedirection, and when thus energizedcontact fingers17- and 18 are-swung to the right so that" contacts 17-5 and 18 8 are closed; these contacts are accordingly termed the reverse contacts of therela' When-the track winding 2 is" de energized, contact fingers 17' and 18 occupy intermediate posi tion's" wherein the backcontacts 17 and 18-7 are closed.

I Each track section is provided with means for supplying current of one-relativepolaw ity or the other to th'e tra c'k rail's of th'e'section, and as here shown, this is accomplished by controlling the polarity of thecurrent supplied to the primary winding of each transformer U. Referring particularly to transformer U the'middle'poin't of thepr imary 12' of this transformer is constantly. connected by a' wire 26 with theright-hand terminal of the secondary 15- of" a transformer T and the left-hand terminal of secondary 15"is-' connected with one end or the other of primary 12 according as relay X isenergized or de=energizeda When relay X isde-energized; so that itsba'clrcon tact 18--7 is closed, the left-hand terminal ofsecondary- 15 is connected with the righthand terminal of primary 12- through wires 23" and 24, back contact IS -7' on relayX andwire 25; The currentwhich'isthen sup plied to the track rails ofthe section A'B is of reverse relative polarity. When track relay X is energized innormal direction so' that contact 18-6 is closed, the left-handterminal of secondary 15 is connected with the left-hand terminal of primary 12 through wires 23 and 24, contact 18-6, wires 28 and 27, to primary 12. When relay X is energized in reverse direction the path is the same as that just traced except that it includes reverse contact 18 8 and omits wire 28. Vfith relay X energized in either normal or reverse direction, the current which is supplied to the track rails of section AB will be of normal relative polarity.

Each track section is provided with a signal designated by the reference character S with an exponent corresponding to the loca tion, each of which signals comprises three lamps G, Y and R, adapted when lighted to indicate Proceed, Caution and Stop, respectively. Each signal is controlled by the associated relay R, the circuits being as follows:

Considering signal S for example, the circuit for the proceed lamp G passes from the secondary 15 of transformer T through wires 23 and 29, normal contact 173 of relay X wire 30, lamp G, and wires 21 and 22 to the secondary 15 of transformer T This-circuit is, of course, closed only when relay K is energized in the normal direction. The circuit for the caution lamp Y of signal S is from the secondary of transformer T through wires 23 and 29, reverse contact 17-5 of relay X wire 81, lamp Y, and wires 21 and 22 to the secondary of transformer T This circuit is closed only when relay X is energized in reverse direction. The circuit for the stop lamp It of signal S is from the secondary of transformer T through wires 23 and 29, back contact 17-4: of relay X wire 32 andimpedance 9, wire 38, lamp R and wires 21 and 22 to the secondary of transformer T This circuit is closed only when track relay X is de-energized.

As shown in the drawing, the track circuit AB is occupied by a car or train V, so that relay X is de-energized with the result that current of reverse relative polarity is supplied to the rails of section B-O. Track relay X is therefore energized in reverse direction, so that the caution lamp Y of signal S is lighted.

I will now assume that the car or train V passes out of section AB and into the section immediately to the left of point A. As this car or train leaves section AB track relay X will become energized in reverse direction, thereby causing current of normal relative polarity to be supplied to the rails of section 13-0 with the result that the con tact fingers of relay X will shift from their reverse positions to their normal positions, so that lamp Y of signal S will become extinguished and lamp G of this signal will become lighted.

. It will be noted that during the reversal of the relay contacts just referred to, the

back contact 17-4E will be closed momen- V tarily, so that the circuit for the stop lamp R of signal S is momentarily closed. In the absence of any preventive means this would result in the momentary lighting of the stop. lamp R,that is, the signal would momentarily indicate stop. This is undesirable, and to prevent such momentary lighting of the lamp R I have included in series with this lamp the impedance 9 which may be, for example, a resistance, a reactance or a condenser. As here shown it is a reactance. The value of this impedance is such that the amount of current supplied to the lamp R during the brief interval in which contact 17 .i is closed is not suflicient to bring this lamp up; to full illumination. The lamp R is preferably a tungsten filament lamp which, as is well understood, has a lower resistance when cold than when it is hot, and the value of the impedance 9 is preferably such that the initial rush of current in the lamp B when contact 174c closes is substantially the same as the amount of current taken by this lamp when the lamp is hot. By proportioning the elements of the lamp R in this manner the lamp will not be lighted during the momentary closure of contact 17-4 while relay R is shifting from either extreme position to the other due to reversal of relative polarity of the current in the track rails.

Although I have herein shown and de scribed only one form of signaling system embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a relay capable of energization in opposite directions, and having a contact which is closed when the relay is deenergized and is also closed momentarily when the direction of energization of the relay is reversed, a signal comprising a lamp controlled by said contact, and an impedance included in the circuit of said lamp for preventing the lighting of said lamp during reversal of said relay.

2. In combination, a relay capable of energization in opposite directions, and having a contact which is closed when the relay is deenergizcd and is also closed momentarily when the direction of energization of the relay is reversed, a signal comprising a lamp controlled by said contact, and a react-ance included in the circuit of said lamp for preventing lighting of the lamp during reversal of said relay.

3. In combination, a relay capable of energization in oppositedirections, a normal contact closed when the relay is energized in one direction, a reverse contact closed when the relay is energized in the other direction, a third contact closed When the relay is deenergized and also closed momentarily When the direction of energization of the relay is reversed, a light signal comprising proceed, caution and stop lamps controlled respectively by the normal, reverse and third contacts of said relay, and a reactance included in circuit with said stop lamp for delaying the lighting of the lamp to full brilliancy, whereby the said lamp does not flash during reversal of said relay.

In testimony whereof I aflix my si nature.

SAMUEL M. L GAS. 

